Diaphragm Wall Techniques

Diaphragm walls have evolved as a standard technique in specialist foundation engineering, by which a continuous wall is constructed from a series of rectangular overlapping panels. During the excavation, the open trench is stabilized and supported by a thixotropic slurry. Individual panels are excavated by duty-cycle cranes using a diaphragm wall grab or trench cutter. Due to the different construction techniques available, diaphragm walls can now be constructed in all kinds of soils, even in very hard soil formations and also in rock.

 

Key advantages of the technique:

  • Application in difficult and hard soil conditions as well as rock
  • Vibration-free technique
  • Extensive depths are possible (>100m)

 

The main areas of application are retaining and cut-off walls as well as vertical foundation elements.

Cutter Diaphragm Wall

Since its introduction in 1984, the cutter diaphragm walling technique using the BAUER Cutter (BC) has developed rapidly. As a result of the wealth of experience accumulated over the following decades, the challenge being faced today is cutting trenches into extremely hard rock and achieving ever-increasing depths. Through project-specific adaptations of the cutter wheels, high excavation outputs can frequently be achieved. The open trench which is stabilized and supported by a thixotropic slurry is excavated in a continuous operation.

 

The slurry charged with spoil material is conveyed to the surface by a mud pump, which is mounted inside the cutter frame. The charged slurry then passes through a desanding plant. Here, the solid particles are separated out from the support slurry. The cleaned slurry is then pumped back into the slurry circulation system for reuse as support slurry in the trench. With the cutter technique depths > 100 m can be achieved.

Grabbed Diaphragm Wall

To complete a construction site successfully today, high demands are placed on efficiency and cost effectiveness. The DHG (Diaphragm Hydraulic Grab) can meet these requirements. Its advantages over a mechanical grab lie in the high degree of trench verticality as well as easier handling. Due to its high closing forces, its freefall capacity, as well as the wide range of possible configurations, the hydraulic diaphragm wall grab is capable of dealing with a wide range of applications and challenges faced by our customers worldwide.

With the DHG (Diaphragm Hydraulic Grab) technique, trench excavation is carried out in stages. The first stage consists of inserting the grab into the trench, loosening and excavating the soil at the base and removing the excavated spoil material from the trench. The open trench is stabilized by a support slurry. On completion of the trench excavation, joint sections, such as stop-ends, and reinforcing cages are inserted into the trench, which is concreted in a further stage. The support slurry, which is displaced by the concrete, passes through a desanding plant and is then pumped back into the slurry circulation system for reuse in the trench.